1. Field of the Invention
This invention relates to transformers, and in particular, to high frequency power transformers.
2. Description of Prior Art
There has been considerable development activity to increase the frequency of power transformers, particularly for switch mode power supplies. Those modifications which must be made to a transformer to increase its power capacity tend to severely compromise its performance at higher frequencies. If it is optimized for high frequency, its power capabilities are limited. This is particularly true for transformers having larger turns ratios, or transformers which must have high dielectric isolation.
A number of transformer designs have been published using "planar" technology, in which the windings of the transformer are fabricated of foil or sheet stock. Interleaving of the windings has been used to improve coupling.
U.S. Pat. No. 4,665,357, Herbert, May 12, 1987, teaches the art of matrix transformers. A matrix transformer is made of a plurality of interdependent magnetic circuits, arranged in a matrix, between and among which electrical conductors are interwired, the whole cooperating to behave as a transformer. The matrix transformer has several advantageous features, among them compact size, good heat dissipation and high current capability. A matrix transformer can be very flat indeed, nearly planar, and can be built using printed circuit board techniques. A matrix transformer can insure current sharing between parallel power sources, and/or between parallel loads.